Comparison of capsulorhexis resistance to tearing with and without trypan blue dye using a mechanized tensile strength model

Abstract

To evaluate the influence of trypan blue staining on capsulorhexis tear resistance using a model for mechanical measurement of the entire capsular bag of fresh human cadaver eyes. John A. Moran Eye Center, University of Utah, Salt Lake City, Utah, USA. Experimental study. After the cornea and iris were removed, a 5.0 to 5.5 mm anterior continuous curvilinear capsulorhexis (CCC) was created; the capsule in study eyes was stained with trypan blue. The nucleus was hydroexpressed and the capsular bag was evacuated by irrigation/aspiration. Two metal shoetree-shaped fixtures were implanted separately in the capsular bag and assembled using a screw nut. After zonulectomy, the fixture-capsular bag assembly was removed from the eye and loaded onto a mechanized tester. The fixtures were separated at a velocity of 7.0 mm/min in 0.15 μm intervals to stretch the capsulorhexis to its rupture point. A graph was generated for each eye. Ten study eyes were compared with 23 control eyes. The groups were comparable in donor age, time from death, and CCC diameter. The mean rupture load was 0.40 Newton (N) ± 0.13 (SD) in the trypan blue group and 0.39 ± 0.16 N in the control group (P=.94). The mean extension was 5.70 ± 0.99 mm and 5.85 ± 1.17 mm, respectively (P=.74). There was no difference in CCC strength between trypan blue-stained capsules and control capsules. Staining with trypan blue did not reduce CCC tear resistance. No author has a financial or proprietary interest in any material or method mentioned.